matrix column element limiting

8 Lug 2015
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Risposta accettata
Aggiornato 8 Lug 2015
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hi,
I have a matrix say 200*30. I need to limit the elements of 29th and 30th columns with different constraints. how can I do that?
thanks,

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Azzi Abdelmalek
Azzi Abdelmalek il 8 Lug 2015

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Example
A=rand(200,30)
idx=A(:,29)>0.5 & A(:,30)<0.7
out=A(idx,:)

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mehrdad asadi
mehrdad asadi il 8 Lug 2015
thanks,
but I actually need to modify the elements!
for example if A(:,30)>1, then I should replace it with 1.
is it possible not to use 'if'?
Azzi Abdelmalek
Azzi Abdelmalek il 8 Lug 2015
Modificato: Azzi Abdelmalek il 8 Lug 2015
You don't need a loop
idx=A(:,30)>1
A(idx,30)=1
mehrdad asadi
mehrdad asadi il 8 Lug 2015
thank you A.Abdelmalek,
I did this, but because I have 4 constraints, and it should be repeated many times in a for loop, it seems it's not that much optimized! thanks anyway, right now, this is the only solution that crosses the mind.
Stephen23
Stephen23 il 8 Lug 2015
Modificato: Stephen23 il 8 Lug 2015
Azzi Abdelmalek's solution is much more optimized than using a loop. This is how MATLAB works best, using basic code vectorization and indexing.

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